Melatonin Improves Sleep, Enhances Cognition and Improves Retinal Health in Seniors

VRP Staff

Two new studies indicate that supplementing with the hormone melatonin improves the quality of sleep, enhances memory, and protects against age-related macular degeneration in seniors.

Melatonin production declines as we age and in several diseases, most notably Alzheimer’s disease, which is associated with a steep decline in melatonin production.

In the first study, a review, the authors point out that treatment of circadian rhythm disorders has led to the development of a new type of agent called "chronobiotics," among which melatonin is the prototype. They discuss how studies have shown that in elderly insomniacs, melatonin treatment decreased sleep latency and increased sleep efficiency, particularly slow-wave sleep. Melatonin’s effect on sleep is the consequence of increasing sleep propensity and of synchronizing the circadian clock.

The reviewers also state that roughly 45 percent of Alzheimer’s patients have disruptions in their sleep accompanied by "sundowning" agitation. Generally, melatonin treatment decreases sundowning in Alzheimer’s patients and reduces variability of sleep onset time. Both open and controlled studies, the reviewers noted, have indicated a significant decrease of cognitive deterioration in Alzheimer’s patients treated with melatonin. The mechanism behind its beneficial effects on cognitive function in these patients could have to do with melatonin’s ability to promote slow-wave sleep in the elderly and its ability to augment the restorative phases of sleep. In addition, melatonin protects neurons against beta-amyloid toxicity and the development of amyloid plaques are associated with Alzheimer’s disease.

According to the reviewers, “Melatonin provides an innovative neuroprotective strategy to reduce the cost of lifetime treatment of some neuropsychiatric disorders.”

In a second study, another group of researchers investigated the effect of melatonin on age-related macular degeneration (ARMD). They decided to undertake the study because melatonin has been shown to control eye pigmentation and thereby regulate the amount of light reaching the photoreceptors. In addition, melatonin scavenges free radicals and protects retinal pigment epithelium cells from oxidative damage. Consequently, the age-related decrease in melatonin could be an important factor in the dysfunction in retinal pigment epithelium cells known to cause the initiation of ARMD.

The researchers treated 100 ARMD patients with 3 mg melatonin given orally each night at bedtime for at least three months. The patients were diagnosed with either the dry or wet form of ARMD. Fifty-five patients were followed for more than 6 months. At 6 months, researchers noted that the visual acuity in melatonin-treated patients generally remained stable, a result already better than the otherwise estimated natural course. Furthermore, the researchers called the beneficial change in the interior eye surface "remarkable" in the melatonin-treated subjects. In addition, after melatonin treatment, only 8 eyes showed retinal bleeding and 6 eyes retinal excretion of fluids and pus. The majority of the melatonin-treated patients experienced reduced pathologic macular changes. No significant side effects were observed.

“We conclude that the daily use of 3 mg melatonin seems to protect the retina and to delay macular degeneration,” the study authors wrote.

References:
Cardinali DP, Furio AM, Reyes MP. Clinical perspectives for the use of melatonin as a chronobiotic and cytoprotective agent. Ann NY Acad Sci. 2005 Dec;1057:327-36.

Yi C, Pan X, Yan H, Guo M, Pierpaoli W. Effects of melatonin in age-related macular degeneration. Ann NY Acad Sci. 2005 Dec;1057:384-92.